Event: QOF event handlers.
[Query Object Framework]


Files

file  qofevent.h
 QOF event handling interface.

Defines

#define QOF_MAKE_EVENT(x)   (1<<(x))
 Allow application-specific events to be created.
#define QOF_EVENT_BASE   8

Typedefs

typedef gint QofEventId
typedef void(* QofEventHandler )(QofEntity *ent, QofEventId event_type, gpointer handler_data, gpointer event_data)
 Handler invoked when an event is generated.

Functions

gint qof_event_register_handler (QofEventHandler handler, gpointer handler_data)
 Register a handler for events.
void qof_event_unregister_handler (gint handler_id)
 Unregister an event handler.
void qof_event_gen (QofEntity *entity, QofEventId event_type, gpointer event_data)
 Invoke all registered event handlers using the given arguments.
void qof_event_suspend (void)
 Suspend all engine events.
void qof_event_resume (void)

Default events for backwards compatibility.

These defaults merely replicate previous behaviour, any process can define their own events.

Note:
events 6, and 7 are "undefined" as of v0.6.3 for future libqof1 or libqof2 usage.


#define QOF_EVENT_NONE   (0)
#define QOF_EVENT_CREATE   QOF_MAKE_EVENT(0)
#define QOF_EVENT_MODIFY   QOF_MAKE_EVENT(1)
 an entity is about to be modified.
#define QOF_EVENT_DESTROY   QOF_MAKE_EVENT(2)
#define QOF_EVENT_ADD   QOF_MAKE_EVENT(3)
#define QOF_EVENT_REMOVE   QOF_MAKE_EVENT(4)
#define QOF_EVENT_COMMIT   QOF_MAKE_EVENT(5)
 an entity has been modified.
#define QOF_EVENT__LAST   QOF_MAKE_EVENT(QOF_EVENT_BASE-1)
#define QOF_EVENT_ALL   (0xff)

Define Documentation

#define QOF_EVENT_BASE   8

Allow scope for more defaults in future. Additional event identifiers must be based on this when using QOF_MAKE_EVENT().

Definition at line 57 of file qofevent.h.

#define QOF_EVENT_COMMIT   QOF_MAKE_EVENT(5)

an entity has been modified.

Added for QofUndo so that the altered state of an entity can be stored to allow the change to be undone and then redone.

Since:
0.7.0

Definition at line 92 of file qofevent.h.

#define QOF_EVENT_CREATE   QOF_MAKE_EVENT(0)

an entity has been created.

Definition at line 71 of file qofevent.h.

#define QOF_EVENT_DESTROY   QOF_MAKE_EVENT(2)

an entity is about to be destroyed.

Definition at line 81 of file qofevent.h.

#define QOF_EVENT_MODIFY   QOF_MAKE_EVENT(1)

an entity is about to be modified.

In addition to previous usage, can used for QofUndo so that the original state of an entity can be stored before modification to allow the change to be undone and then redone.

Definition at line 79 of file qofevent.h.

#define QOF_EVENT_NONE   (0)

init value - invalid.

Definition at line 69 of file qofevent.h.

#define QOF_MAKE_EVENT (  )     (1<<(x))

Allow application-specific events to be created.

Used together with QOF_EVENT_BASE to simplify creation of application events without interfering with any new events added within QOF.

#define APP_EVENT_A QOF_MAKE_EVENT(QOF_EVENT_BASE+0)
#define APP_EVENT_B QOF_MAKE_EVENT(QOF_EVENT_BASE+1)

Definition at line 53 of file qofevent.h.


Typedef Documentation

typedef void(* QofEventHandler)(QofEntity *ent, QofEventId event_type, gpointer handler_data, gpointer event_data)

Handler invoked when an event is generated.

Parameters:
ent,: Entity generating the event
event_type,: The id of the event, including additional identifiers and the older defaults.
handler_data,: data supplied when handler was registered.
event_data,: data to be supplied when handler is invoked.

Definition at line 104 of file qofevent.h.

typedef gint QofEventId

Define the type of events allowed.

Definition at line 40 of file qofevent.h.


Function Documentation

void qof_event_gen ( QofEntity entity,
QofEventId  event_type,
gpointer  event_data 
)

Invoke all registered event handlers using the given arguments.

Certain default events are used by QOF:

  • QOF_EVENT_DEFAULT_CREATE events should be generated after the object has been created and registered in the book.
  • QOF_EVENT_DEFAULT_MODIFY events should be generated whenever any data member or submember (i.e., splits) is changed.
  • QOF_EVENT_DEFAULT_DESTROY events should be called before the object has been destroyed or removed book.

Any other events are entirely the concern of the application.

Note:
QofEventHandler routines do NOT support generating events from a GUID and QofIdType - you must specify a genuine QofEntity.
Parameters:
entity,: the entity generating the event
event_type,: the name of the event.
event_data,: Data to be passed to the event handler just for this one event. Can be NULL.

Definition at line 235 of file qofevent.c.

00236 {
00237     if (!entity)
00238         return;
00239 
00240     if (suspend_counter)
00241         return;
00242 
00243     qof_event_generate_internal (entity, event_id, event_data);
00244 }

gint qof_event_register_handler ( QofEventHandler  handler,
gpointer  handler_data 
)

Register a handler for events.

Parameters:
handler,: handler to register
handler_data,: data provided when handler is invoked
Returns:
id identifying handler

Definition at line 72 of file qofevent.c.

00073 {
00074     HandlerInfo *hi;
00075     gint handler_id;
00076 
00077     ENTER ("(handler=%p, data=%p)", handler, user_data);
00078 
00079     /* sanity check */
00080     if (!handler)
00081     {
00082         PERR ("no handler specified");
00083         return 0;
00084     }
00085 
00086     /* look for a free handler id */
00087     handler_id = find_next_handler_id ();
00088 
00089     /* Found one, add the handler */
00090     hi = g_new0 (HandlerInfo, 1);
00091 
00092     hi->handler = handler;
00093     hi->user_data = user_data;
00094     hi->handler_id = handler_id;
00095 
00096     handlers = g_list_prepend (handlers, hi);
00097     LEAVE ("(handler=%p, data=%p) handler_id=%d", handler, user_data,
00098         handler_id);
00099     return handler_id;
00100 }

void qof_event_resume ( void   ) 

Resume engine event generation.

Definition at line 156 of file qofevent.c.

00157 {
00158     if (suspend_counter == 0)
00159     {
00160         PERR ("suspend counter underflow");
00161         return;
00162     }
00163 
00164     suspend_counter--;
00165 }

void qof_event_suspend ( void   ) 

Suspend all engine events.

This function may be called multiple times. To resume event generation, an equal number of calls to qof_event_resume must be made.

Definition at line 145 of file qofevent.c.

00146 {
00147     suspend_counter++;
00148 
00149     if (suspend_counter == 0)
00150     {
00151         PERR ("suspend counter overflow");
00152     }
00153 }

void qof_event_unregister_handler ( gint  handler_id  ) 

Unregister an event handler.

Parameters:
handler_id,: the id of the handler to unregister

Definition at line 103 of file qofevent.c.

00104 {
00105     GList *node;
00106 
00107     ENTER ("(handler_id=%d)", handler_id);
00108     for (node = handlers; node; node = node->next)
00109     {
00110         HandlerInfo *hi = node->data;
00111 
00112         if (hi->handler_id != handler_id)
00113             continue;
00114 
00115         /* Normally, we could actually remove the handler's node from the
00116            list, but we may be unregistering the event handler as a result
00117            of a generated event, such as GNC_EVENT_DESTROY.  In that case,
00118            we're in the middle of walking the GList and it is wrong to
00119            modify the list. So, instead, we just NULL the handler. */
00120         if (hi->handler)
00121             LEAVE ("(handler_id=%d) handler=%p data=%p", handler_id,
00122                 hi->handler, hi->user_data);
00123 
00124         /* safety -- clear the handler in case we're running events now */
00125         hi->handler = NULL;
00126 
00127         if (handler_run_level == 0)
00128         {
00129             handlers = g_list_remove_link (handlers, node);
00130             g_list_free_1 (node);
00131             g_free (hi);
00132         }
00133         else
00134         {
00135             pending_deletes++;
00136         }
00137 
00138         return;
00139     }
00140 
00141     PERR ("no such handler: %d", handler_id);
00142 }


Generated on Mon Jul 13 05:15:22 2009 for QOF by  doxygen 1.5.9